fix completion of "--"

[starius]

What type of PR is this?

(REQUIRED)

• bug

What this PR does / why we need it:

(REQUIRED)

Currently "--" is completed to "--help," (note the comma!)
This PR fixes it so it completed to "--help" without the comma.

Which issue(s) this PR fixes:

(REQUIRED)

Fixes #1993
Reverts #1933

Special notes for your reviewer:

(fill-in or delete this section)

If the approach is accepted it makes sense to fix this in v2 as well.

Testing

(fill-in or delete this section)

You can compile the example given for completion here: https://cli.urfave.org/v3/examples/completions/shell-completions and verify what happens you you type "greet --" and press TAB.

Release Notes

(REQUIRED)

Fixed auto-completion of double dash (--)

[abitrolly]

-- is often used to separate arguments. I would expect -- to complete to itself in this case.

[starius]

@abitrolly if -- completes to itself, how to see the list of available flags?

Check how common tools behave when TAB is pressed after --:

$ git clone https://github.com/urfave/cli/ --
--also-filter-submodules   --mirror                   --separate-git-dir=
--bare                     --no-...                   --server-option=
--branch=                  --no-checkout              --shallow-exclude=
--bundle-uri=              --no-hardlinks             --shallow-since=
--checkout                 --origin=                  --shallow-submodules 
--config=                  --progress                 --shared 
--depth=                   --quiet                    --single-branch 
--dissociate               --recurse-submodules       --sparse 
--filter=                  --reference=               --tags 
--hardlinks                --reference-if-able=       --template=
--ipv4                     --ref-format=              --upload-pack=
--ipv6                     --reject-shallow           --verbose 
--jobs=                    --remote-submodules        
--local                    --revision=

In zsh completion if urfave/cli is used it even prints a description for each option.

[starius]

@dearchap I suspect that my fix is not sufficient to completely fix -- case. I noticed that it can run the tool itself if trying to complete a subcommand while specifying flags for the parent command. (I.e. a completion attempt was interpreted as if the current command itself was called.)

I tried to reproduce this in tests and wrote this:

func ExampleCommand_Run_shellComplete_bash_withDoubleDashFlag_Subcommand() {
        cmd := &cli.Command{
                Name:                  "greet",
                EnableShellCompletion: true,
                Flags: []cli.Flag{
                        &cli.Int64Flag{
                                Name:    "other",
                                Aliases: []string{"o"},
                        },
                        &cli.StringFlag{
                                Name:    "xyz",
                                Aliases: []string{"x"},
                        },
                },
                Commands: []*cli.Command{
                        {
                                Name:        "subcmd",
                EnableShellCompletion: true,
                                Flags: []cli.Flag{
                                        &cli.Int64Flag{
                                                Name:    "aaa",
                                        },
                                        &cli.StringFlag{
                                                Name:    "bbb",
                                        },
                                },
                        },
                },
        }

        // Simulate a bash environment and command line arguments
        os.Setenv("SHELL", "bash")
        os.Args = []string{
                "greet", "--other", "1",
                "subcmd", "--",
                "--generate-shell-completion",
        }

        _ = cmd.Run(context.Background(), os.Args)
        // Output:
        // --aaa
        // --bbb
        // --help
}

This should return the list of options, but it produces the help message instead.

Could you help with this one, please? Maybe I'm missing something.